You can get a drill bit from most auto shops that is made for drilling out spot welds. They havd a flat cutting surface with a 'point' in the centre, line this up with the centre of the tack and drill down untill you have gone through the first layer of steel. Then use a steel chisel, place it between the tack welded parts and gently tap them appart with a hammer. I can take a rad support off a car in about half an hour like this.
PS, DONT drill completely through both sheets of steel that are tacked together! And there called Cobalt bits the ones I am refering to.
There are several purpose made tools for spot weld drilling.I use a Sykes- Pickavant "Zip cut spot weld remover #04001100." when you are unpicking panels you need a good tool to keep going and not be held up with breakages etc . This little thing is perfect. http://www.sptools.co.uk/catalogue
Mike, I've got 2 kinds at the shop, the "mini-holesaw" type, and the solid carbide type. The solid one works better in most applications, though not all. Won't break as easily, either. Got it at Eastwood, but I'm sure you can find it cheaper elsewhere.
i only have the mini holesaw type, and a very old arbor for it...but I discovered that drilling a 3/32" hole first will keep it centered
I like to use the Blair spot weld bit. It's a mini "hole saw" style cutter, but has a spring loaded locating pin in the center. Both the saw and pin are replaceable. I center-punch the spot weld first to locate it. They are available at any body shop jobber.
The one I have has that same spring loaded center pin, but it is hard to keep it centered with just a center punch dimple...it'll take off when the blade grabs on one side, and break the blade....drilling a little hole first seems to work a lot better.
This type of bit is the best, its kid of a brad point drill bit for metal. They work great for anything I have ever done. I dont think this is the one that I have but looks the same. http://www.autobarn.net/xxxw-dfxdf1480.html
If you have trouble finding all of the spot welds lightly run a disc sander over the area (most likely a flange), the spot welds will show up quickly. Have fun. Alden
Grind the point on a HSS drill bit to make it look more like a spade bit and rill only thru the top layer. You'll need a grinding wheel with sharp edges.
Using a grinding wheel with sharp edges grind the point of a HSS drill bit to look like a brad point drill. When drilling I found it quicker to first drill out the center of the spot weld with a small center drill. Then I used my home made bit. Hope this photo helps. Click on it to make bigger.
That looks like a good way to to it, and cheap too if you have some old drill bits laying around. Nice suggestion!
I also use the blair spot weld cutters but the larger heavy duty version, and i pre drill with a 1/8" bit to center them, works great and very little breakage.
yeah, mopars are like that, but chevys had damn good welds! (except for my 57 suburban that had half the firewall spot welds break)
No offense to DocWatson, but..... If you have easy welding access to the back side of the pieces you're separating, it's about as easy to drill thru both pieces---then you have a hole already in the right place to plug weld. Not always applicable, but it saves panel alignment and drill time when it is.
Hey, Another method of locating spot welds to be drilled out is to take a torch and a wire brush (don't tell me I need to tell you to ware eye protection) and burn off the paint covering the spot weld. The hole saw type drill bits are available from auto body supply outlets, but if you have a shit load of spot welds to drill, center punch the weld, than take a sharp 1/4 or 3/8, depending on the size of the weld, bit and drill through the top layer and well into the bottom layer. Now would be a good time to teach yourself how to grind drill bits properly. It will save ya a good bit of money and grief! Happy Xmas Happy Whatever
Squirrel, must not have had much experence with the 70s and newer Chevy pickups. A bunch of the spot welds on those were not real good. Actually, I've replaced a lot of floor pans and suspension structures on all brands of cars and trucks, foreign and domistic. My guess is probably 25% of the spot welds from the late 60s and newer cars of nearly all brands have little to no penatration. Seems the older stuff was better welded. The 90s and up stuff have really crappy welds and very poor pannel fit, but most of it is covered with that putty/seam sealer they love to load on there. BTW, I use a 5/16 regular drill bit for spot welds. Gene
No offence taken! You raise a good point that I didnt think off. We had a spot welder so needed the steel to be there, if your just doing it with a mig (Etc..) yes you will need to drill through to plug weld.....
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